Modern military vehicles carry an increasing number of electronic components designed, inter alia, to find possible targets, detect and counter enemy attempts to locate and identify the vehicle, and to manage performance of the vehicle. Such vehicles typically carry a number of instruments whose control panels contain manually adjustable dials or knobs rotatable upon shafts threaded to openings in the panel, and it is often critical that these dials or knobs are prevented from wandering even slightly from their settings. The vehicles and their components are subjected to severe vibrations and consequently a spring is commonly compressed between a collar on the threaded shaft and the face of the panel. The spring axially forces together the complimentary threads of the shaft and panel, thereby inhibiting the turning of the knobs or dials by the vibrations. In many cases, however, the nature and intensity of the vibrations is such that a spring alone may not suffice to prevent dial movement, particularly when a vehicle vibration sets up a harmonic vibration in the spring. Unwanted dial movement may also occur, if the spring/dial assembly is vibrated in two directions at once, so that one vibration bends the spring along its central axis as another vibration moves shaft threads relative to panel opening threads within a typical interthread clearance.
My invention is an arrangement wherein the dial is prevented from rotating even under the severe vibrational conditions described above. The invention is a pair of interdigitated sleeves rotatable on the axis of the dial shaft. The sleeves encage a coil spring which inhibits rotation of the shaft in a known manner relative to a substrate or body into which the shaft is threaded. My invention can not only be used on electronic instruments as described above, but can also be used on set screw arrangements and screw type metering valves for precise control of a fluid under intense vibrational conditions.